Keratoconus is a relatively uncommon eye condition where the cornea becomes thinner and bulges forward. The term “keratoconus” comes from the Greek terms for cornea (“kerato”) and cone-shaped (“conus”). The exact cause of keratoconus remains unknown, but it appears that oxidative damage from free radicals plays a role.
Gas permeable contact lenses are the treatment option of choice for mild and moderate keratoconus. Because they are rigid, GP lenses can help contain the shape of the cornea to prevent further bulging of the cornea. They also can correct vision problems caused by keratoconus that cannot be corrected with eyeglasses or soft contacts.
In some cases, a soft contact lens is worn under the GP lens for greater comfort. This technique is called “piggybacking.” Another option for some patients is a hybrid contact lens that has a GP center, surrounded by a soft “skirt”.